How can the U.S. Government official fuel economy website make a statement like this? "Quick acceleration and heavy braking can reduce fuel economy by up to 33 percent on the highway and 5 percent around town. New EPA tests account for faster acceleration rates, but vigorous driving can still lower MPG." It's the first paragraph at Many Factors Affect MPG Isn't it the other way around 33% in the city and 5% on the highway?
It means stop and go traffic in the highway, basically like driving in in city. While in the city, the lost of efficiency is less due to already low MPG>[ quote="briank101, post: 1858212, member: 92812"]How can the U.S. Government official fuel economy website make a statement like this? "Quick acceleration and heavy braking can reduce fuel economy by up to 33 percent on the highway and 5 percent around town. New EPA tests account for faster acceleration rates, but vigorous driving can still lower MPG." It's the first paragraph at Many Factors Affect MPG Isn't it the other way around 33% in the city and 5% on the highway?[/quote]
Granted in an extreme hypothetical case one could create a 0-60, 60 to 0, 0-60, over and over for the 33% highway and then what is the likelihood the same typical set of drivers would have pristine preservation of momentum skills in the city to only get a 5% reduction. On the face value the statement got they numbers reversed. Remember that the fueleconomy.gov site is geared towards average typical drivers and and statements such as this will increase confusion. I don't how many efficient driver "want-to-be's" think overall fuel consumption is proportional to acceleration rate and not think anything about a rapidly braking which is where nearly all the negative fuel economy impact lies in city driving. If I want I can get 25 mpg by accelerating slowly and braking rapidly, I also can get 80 mpg (which I get in the the 20 mile city portion of my drive everyday) by accelerating quite rapidly (faster than 90 % of traffic) by focusing my attention on not having to use the brakes, it's not how fast you accelerate, it's how long. In terms of return on mpg improvement, it's the lowest hanging fruit, and the heavier and more fuel inefficient the vehicle, the bigger the amount of fuel saved using this technique.
To add it pisses me off driving behind Prius's that accelerate too slowly falsely thinking they're improving their fuel consumption. I probably piss off drivers when I take I foot off the gas when I see the light turn to yellow 400 yards down the road but at least this is really saving gas. If I happen to be first car at the light and all the others have moved to the lane beside me assuming I will accelerate as slowly as I coasted to the stop, I am 90% of the time first up to full speed again...... Just venting......
Rapid acceleration will hurt your mileage in a Prius just like in any other car. You can see this with an OBD device and the AVG segment mileage readout. Accelerating at 1/4 above ECO will be more efficient than at 3/4 above. The Prius gets most of it's efficiencies from the regeneration system and the Synergy firmware, not the engine. I also would like to see some more information on avoiding braking. It is not at all clear that it improves mileage. The interaction between the charge state of the battery and the rest of the systems is, I think, more complicated than just "don't brake".
